This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our studies are directed at defining the neural substrate for visual processing related to normal and pathological smooth pursuit eye movements and gaze-holding. In studies of normal monkeys we have demonstrated that volitional saccades modulate the visual sensitivity of responses in MSTd, including significantly shortening visual latency. We also demonstrated that neurons in MSTd carry a signal related to eye velocity during smooth pursuit and ocular following. This work is significant in showing that MST, which is a multimodal cortical area, plays a role in both monitoring and generating eye movements. Our complimentary studies in strabismic monkeys show that MSTd neurons have strong ocular preferences unlike that found in normal monkeys. Therefore, MST is an important node in the cortical pursuit system and is sensitive to the quality of early visual experience and development of sensory-motor function in primates.